Question: Which is the occupational carcinogen for the polymer of polyvinyl chloride?
Paraphrase: Which is the word related carcinogen for the polymer of polyvinyl chloride?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q146368 wdt:P4600 ?obj . ?obj wdt:P31 wd:Q21074597 } 
Answer: vinyl chloride